Sculpting refinement after a boolean subtraction

[Anonymous]

Hi,

This is a curly one. I am trying to sculpt an object from 2 bodies inside of 1 component. Once they are molded together in the sculpt environment, I need to very accurately subtract some material. I then need to be able to go back and adjust the sculpted body AFTER the subtraction has been done, so as to further refine the sculpted object. 

Is there a suitable workflow I am missing to be able to do this?

I have included the model. Warning, it is a bit of a jumbled mess of operations as I was trying to get to where I needed to go, apologies...

[laughingcreek]

just double click on the tspline feature in the timeline, make your edits, and exit.

looks like you lost your symmetry, you may want to get that back.

if you want to be able to visualize where the cuts are going to be, roll the time line back to before you used the combine, then the bodies will be ghosted while your making the edits.  some times I keep my tools for cut combine like this so I can turn them back on just for that reason.

[Anonymous]

I understand what you are saying, but what I'm struggling with is doing further sculpting after the boolean is done to the object. I cannot achieve all I need to in either environment, so would love to be able to switch between design and model environments to evolve the design in real time.

If I edit the sculpt feature in the timeline I can only edit that particular form, not what I need to once the design operations are done to it... 

[laughingcreek]

Do you mean you want the tspline to be magically shaped like the solid body is after you make the cuts?  No, there isn't a workflow for that.  That would be a neat trick.

[Anonymous]

Yes, it would, and hopefully Fusion will someday be able to read our design thoughts to translate them directly... 🙂 

What I am saying is that once the design edits are done to the sculpted body, why does fusion not allow you to build on what you have just done by seamlessly moving back and forth between environments to refine your most current operation?

It is very difficult to progress forward with a complex object if you are constantly having to go backwards to adjust the original (in sculpt mode), instead of allowing the user to refine the part in its most current state - namely after further design edits have been done to it and when returning into sculpt mode. Do you follow me?

[TrippyLighting]

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@Anonymous wrote:

... why does fusion not allow you to build on what you have just done by seamlessly moving back and forth between environments to refine your most current operation?

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Because T-Splines and NURBS are two different types of geometry. T-Splines are just a one-directional intermediary between a mostly-quad mesh and NURBS surfaces. 

[Anonymous]

Ok, so while on this topic, I am assuming that the patch mode which does allow for seamless and real-time integration with the design environment is NURBS based as well?..

I guess what you're telling me is that there is simply no way that these 2 types of geometry can operate interchangeably? Why is it then that a sculpted body can be converted back to a NURBS body when taken back into the design environment, but not the other way around. If the coding is there to allow conversion one way, why is it not possible to reverse it again when taken back into the sculpt environment?...

[TrippyLighting]

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@Anonymous wrote:

...why is it not possible to reverse it again when taken back into the sculpt environment?...

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Because you modified it 😉

Let me explain.,,

The shape of natural (untrimmed) NURBS surfaces, Sub-D surfaces and T-Splines are controlled by a quadratic mesh of control vertices (CVs). They are mathematically similar (but not equal!). That similarity allows to convert a Sub-D control mesh to be converted into T-Spline and vice versa. You might have noticed the "Save control cage as .obj" when working in a Form/Sculpt feature. You can also import a .obj file you might have created Maya into Fusion 360 can convert it into a T-Spline and then NURBS. T-Splines provide the math and algorithms to convert a quad mesh into untrimmed NURBS surfaces.

When you convert the T-Spline into a NURBS surface in Fusion 360 and then modify these objects, however, that creates trimmed NURBS surfaces. Those can only be converted back into a T-Spline  in special circumstances and that conversion does not represent the original quad mesh.

[Anonymous]

Thanks for the explanation. Does all that mean that Fusion will never be able to convert the modified NURBS object back into the sculpt environment?

Would you be able to suggest an alternative method of achieving my goals that Fusion can accommodate?

[Anonymous]

I think I just understood what you were saying... If I were to prepare every sketch I would need to complete the entire part, before going into sculpt mode, then in theory I can do all I need whilst in there first time around.

The problem with that is the sculpt environment does not allow for boolean operations which are crucial to modifying the part.

One thing I am wondering, is if the sculpt environment was upgraded to allow for both sketching/projecting and boolean functions within the environment (because it cannot seamlessly interact back and forth with the design environment) then you would have an all in one solution....

[laughingcreek]

until re-topology algorithms get a whole lot better than they are now, this won't be possible. 

[Anonymous]

I think they already are.... I look after software like MODO and wonder why is Fusion so far behind...

[TrippyLighting]

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@Anonymous wrote:

I think they already are.... I look after software like MODO and wonder why is Fusion so far behind...

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T-Splines are an intermediate only between a mesh and a NURBS surface. Fusion 360 is a CAD software and the ultimate goal is to have a solid CAD model, not a mesh.

Modo works with meshes only and the boolean operations in modo (which are also possible in Blender BTW) create triangles, so no mathematically precise, resolution free CAD surfaces.

Modo's mesh fusion which is great also only works with meshes and creates triangles, which will prevent you from converting it into T-Splines.

If that's OK for you then that might be a better way to model this. However, I do not believe that your end result requires you to use booleans. You just need to learn how to properly mesh-model this 😉

The T-Spline already could do with some TLC.

[Anonymous]

OK, thanks for the suggestion. I don't quite understand how that helps me model it though, as the same lack of back and forth integration between the two environments exists as it does with the Sculpt environment. There is no allowance for boolean operations or the ability to do a loft to form the shape in the first place...

The sculpt was my first attempt to join the bodies together, hence the imperfect result. I realize my lack of time with Fusion limits my ability to find solutions, I was hoping to perhaps find some help with a usable workflow from the more experienced users... Is it not achievable in Fusion?